Research On Measurement Of Flame Structure And Temperature Distribution Based On Volumetric Imaging

Combustion is a chemical reaction process accompanied by intense light and heat generation,and has important applications in our life,e.g.providing propulsion for aero-engines.When combustion instability happens in the aero-engine,the operation of the engine will be affected.Therefore,it is an important task to monitor the combustion process.Optical diagnostics has been applied extensively due to its noninvasiveness.Among those techniques,computed tomography of chemiluminescence(CTC)and background-oriented Schlieren tomography(BOST)are two important techniques.CTC is mainly used to recover the flame structure and 3D distribution of heat release.BOST is usually used to detect the 3D distributions of refractive index,density and temperature.In this thesis,two models were established i.e.the imaging model of CTC and the calculation model of BOST.At last,a high-speed CTC system using a customized fiber bundle was built to reconstruct the 3D structure of turbulent swirl flames.A BOST system was also set up to simultaneously reconstruct the refractive index,density and temperature of the flame generated by a Benson burner.The results were compared to that measured by thermocouple to assess the feasibility of BOST in the measurement of 3D flame temperature distribution.